The present invention relates to fabrics excellent in conductivity and antistatic property as well as dust proof clothes sewed therefrom, which are electroconductive throughout the dust proof clothes and excellent in durability and antistatic property.
Conventionally, yarn composed of electroconductive (hereinafter referred to xe2x80x9cconductivexe2x80x9d) fibers and non-conductive synthetic fibers is woven into fabrics for dust proof clothes for a measure against static electricity. Fabrics into which yarn containing these conductive fibers has been woven are conductive in the warp and weft directions along which the conductive fibers have been woven, not only in the case where yarn containing conductive fibers is mixed and woven in a striped pattern at predetermined intervals, but also in the case where the yarn is woven in a check-striped pattern, but satisfactory conductance cannot be obtained in a slanting direction of fabric, and therefore, it is difficult to achieve electrical conductance throughout dust proof fabrics. The reason for this is that conductive fiber introduced into the warp and conductive fiber introduced into the weft are in poor electrical contact with each other.
Further, in dust proof clothes formed from these fabrics, it is difficult to achieve electrical conductance in the sewn portions, and it is further difficult to achieve electrical conductance throughout the dust proof clothes.
The reason is that the conductive yarns in the respective fabrics are not in electrical contact with each other even in the sewn portios.
If conductive yarn composed exclusively of conductive fibers is woven in the case where conductive yarn is woven into fabrics, differences in fiber characteristics such as strength, elongation, shrinkage etc. occur between the conductive fibers and other fibers constituting the fabrics, thus readily causing various drawbacks such as fiber cutting, puckering etc. at the time of weaving and processing. Further, because the conductive fibers are more expensive than general fiber materials, it is also important to reduce the amount thereof for use.
Accordingly, conductive fibers are mixed with fibers similar to fibers used in the base constituting fabrics by means of inter-twisting, air confounding etc., and the yarns thus obtained are generally used.
In the case where these conductive yarns are mixed in a striped pattern at predetermined intervals in weaving of fabric, the resulting fabric is conductive in the direction along which the conductive fibers have been woven, but cannot be conductive in other directions.
Further, even in the case where these conductive yarns are woven in a check-striped pattern at predetermined intervals, there is electrical conductance in the directions such as warp and weft directions along which the conductive yarns have been woven, but the conductive yarns woven into the warp and the conductive yarns woven into the weft are not in electrical contact with each other, so it is difficult to achieve satisfactory electrical conductance in a slanting direction of the fabric, and as a result, it is difficult to achieve satisfactory electrical conductance throughout the fabric.
This is caused by the fact that the conductive fibers are buried inside of the yarn so that the contact between the conductive fibers inserted into the yarn as the warp and the conductive fibers inserted into the yarn as the weft is deteriorated.
Further, the conductive fibers are buried inside of the yarn, thus deteriorating antistatic property and simultaneously raising the contact resistance between the conductive fibers and the outside, so the sewn portions in contact under low contact pressure in sewing the fabric are hardly rendered conductive.
As described above, the conventional dust proof clothes suffer from the two problems, that is, fabrics used in each portion of the dust proof clothes cannot achieve good electrical conductance throughout the fabrics, and upon sewing of the respective portions, electrical conductance in the sewn portions cannot be stably obtained, so it is difficult to achieve electrical conductance throughout the dust proof clothes.
As a method of improving antistatic property, JP60-28546A describes a method of improving the performance of dissipating static electricity by raising conductive fibers to the surface of fabric to form a parallel and check-striped pattern. In this prior art method, however, the mutual contact between the conductive fibers formed in the warp and those in the weft are not sufficient, and the electrical conductance of the resulting fabric in a slanting direction is hardly obtained. Further, the conductive fibers are raised to the surface of the fabric, and the conductive fibers have a larger diameter than that of non-conductive fibers in the base constituting the fabric, so there is a problem with abrasion durability.
JP-A 55-135014 describes that for improvement of the electrical conductance of sewn portions in dust proof clothes, the portions to be sewn are sewed such that yarn containing conductive fibers as a part of sewing threads is brought into electrical contact with the end of conductive fibers mixed in fabric.
In this case, however, electrical contact in the sewn portion is sometimes deteriorated when drawbacks such as puckering are appeared in the sewn portion due to repeated wearings and washings.
JP-A 58-160209 describes clothes in which a conductive material is arranged at overlap portions or butted portions of fabric having conductive fibers woven at suitable intervals, so that the respective portions are an electrical contact with one another. In this case, however, there is an economical problem because the conductive material should be arranged at the cloth overlap portions or the butted portions, and there is a further problem with the durability of the conductive material itself to be arranged.
The object of the present invention is to provide fabrics excellent in conductivity and antistatic property as well as dust proof clothes being electrically conductive throughout the dust proof clothes and further excellent in durability and antistatic property, to solve the problems described above.
First, the present invention resides in fabrics comprising warps and/or wefts containing electrically conductive yarn at intervals, characterized in that the electrically conductive yarn is structured by covering synthetic filament yarn as the core with conductive bicomponent fibers.
Second, the present invention resides in the above-described fabrics wherein the conductive yarn is structured by double-covering synthetic filament yarn as the core with conductive bicomponent fibers.
Thirdly, the present invention resides in the above-described fabrics wherein the conductive yarn is contained in both of the warps and wefts at intervals thereof and that in one is structured by double-covering synthetic filament yarn as the core with conductive bicomponent fibers and the other is structured by single-covering synthetic filament yarn as the core with conductive bicomponent fibers.
Fourthly, the present invention resides in the above-described fabrics wherein the conductive yarn is contained in both of the warps and wefts at intervals thereof and that in one is structured by double-covering synthetic filament yarn as the core with conductive bicomponent fibers and the other is double-twisted yarn composed of synthetic filament yarn and conductive bicomponent fibers.
Fifthly, the present invention resides in the above-described fabrics wherein the degree of coverage of the conductive bicomponent fiber in the conductive yarn is 20 to 70%.
Sixthly, the present invention resides in the above-described fabrics wherein the conductive bicomponent fiber comprises carbon and the electric resistance thereof is 106-109 xcexa9/cm.
Seventhly, the present invention resides in the above-described fabrics wherein the conductive bicomponent fiber is obtained by bicomponent spinning a non-conductive base polymer and a matrix polymer containing carbon as conductive component such that at least a part of the latter is exposed to the surface of fibers.
Eighthly, the present invention resides in dust proof clothes comprising the above-described fabrics.
Ninethly, the present invention resides in the above-described dust proof clothes comprising fabrics stitched together using sewing thread containing 30 to 100% by weight of conductive bicomponent fibers containing carbon and having an electric resistance of 106-109 xcexa9/cm.
Tenthly, the present invention resides in the above-described dust proof clothes wherein conductive fibers containing in the sewing thread are obtained by bicomponent-spinning a non-conductive base polymer and a matrix polymer containing carbon as conductive component such that at least a part of the latter is exposed to the surface of fibers.
Eleventhly, the present invention resides in the above-described dust proof clothes wherein the resistance of a portion including sewn portions is 109 xcexa9 or less.
In the fabrics of the invention, the conductive yarn used as the warp and weft is structured by covering synthetic filament yarn as the core with conductive bicomponent fibers, and in particular the conductive yarn used as at least one of the warp and weft is preferably structured by double-covering synthetic filament yarn as the core with conductive bicomponent fibers, and particularly preferably the conductive yarn used as at least one of the warp and weft is structured by double-covering synthetic filament yarn as the core with conductive bicomponent fibers while the other is structured by single-covering synthetic filament yarn as the core with conductive bicomponent fibers.
Synthetic filament yarn used as the core of the conductive yarn may be substantially the same as that constituting the base of fabrics for clothes. Specific examples of its materials include polyester (polyethylene terephthalate etc.), polyamide (nylon 6, nylon 66, etc.) etc., among which the polyester is most preferable for chemical stability and handling property. For example, polyester filament yarn or polyeser finished yarn such as polyester false twisted yarn, which has 0.1 to 5 denier in finesses as single fiber and 50 to 200 denier in total fineness, is preferably used.
The conductive fibers for covering (non-conductive) synthetic filament yarn includes yarns comprising metal-coated synthetic filaments bicomponent fibers obtained by bicomponent spinning a base polymer as fiber substrate and a conductive polymer having fine particles of a conductive material such as carbon, metal or metal compound dispersed in a matrix polymer. The latter bicomponent spun fiber using carbon as a conductive material is most preferable.
Insofar as a part of (the conductive polymer containing) the conductive material in the bicomponent fiber is exposed to the surface, the sectional shape are not particularly limited. One example of its sectional shape is shown in FIG. 1. In FIG. 1, 1 is a base polymer (non-conductive polymer) layer and 2 is an electrically conductive polymer layer.
By way of example, the conductive bicomponent fibers of 1 to 5 denier in finesses as single fiber or of 10 to 200 denier preferably 10 to 100 denier in total fineness is preferably used. It is preferable for friction resistance that conductive bicomponent fiber has a finesses not more than that of yarn constituting the base of textile, and preferably, the resistance thereof is usually 109 xcexa9/cm or less, particularly 108 xcexa9/cm or less.
Conductive yarn is produced by covering preferably double-covering the (non-conductive) synthetic filament yarn as the core with the conductive bicomponent fibers.
The degree of coverage of the conductive fiber in the conductive yarn in the double-covering structure is the proportion of the conductive fiber when viewed from the side of the conductive yarn as shown in FIG. 2, and this degree is shown in the following formula.
Degree (%) of coverage of conductive fiber=area of conductive fiber/area of conductive yarnxc3x97100.
Although the degree of coverage of the conductive fiber is preferably as high as possible, the degree of coverage of the conductive fiber is preferably 20 to 70% in consideration of the processability, manufacturing, costs, conductivity etc. of the conductive yarn. Given 20% or less, the effect of electrical conductance is hardly obtained. In the case of 70% or more, electrical conductance is hardly obtained. In the case of 70% or more, electrical conductance can be sufficiently obtained, but even if the conductive fiber is mixed at such high ratios, no particular effect cannot be obtained, resulting in higher costs.
The degree of coverage of the conductive fiber in the conductive yarn is raised in this manner, and the yarn is structured by double-covering the fiber by simultaneously winding the upper and lower fiber in the opposite direction to generate friction resistance by which the covering conductive fiber can be prevented from slipping at the time of yarn processing and textile manufacturing.
By use of this structure of conductive yarn, physical properties of conductive yarn, such as strength etc. can be secured stably. Further, because the conductive fiber is exposed to the surface of the yarn, the contact between the conductive fiber of the conductive yarn inserted into the warp and the conductive fiber of the conductive yarn inserted into the weft is improved whereby the electrical conductance of fabrics in all-directions including a slanting direction can be secured. Further, if dust proof clothes is made of such fabrics, the contact resistance in sewn portions can be reduced even in contact under low contact pressure in weaving the fabrics, and thus the electrical conductance among the sewn portions can be secured. Further, by such structure, fabrics also excellent in antistatic propeorty can be provided.
Further, the fineness of the conductive yarn is made in the same range as non-conductive fibers constituting other portions in fabrics whereby the friction durability can also be improved without causing the conductive yarn to be protruded from the fabrics.
The pitch of the conductive yarn to be mixed is 1 yarn/3 cm or more, preferably 1 yarn/cm, in both the warp and weft directions.
By such structure, the resistance of fabric measured in the method shown in FIG. 3 can be 106 to 109 xcexa9, and in particular the resistance of fabric in a slanting direction, as measured in the method shown in FIG. 4, can be 106 to 109 xcexa9.
Fabrics using the conductive yarn where the degree of coverage of the conductive fiber is in the above range enable the electrical conductance of the fabrics in all directions and can simultaneously reduce resistance stably to secure excellent electrical control.
By sewing the above fabrics together, it is easy to obtain the electrical conductance among the sewn portions, and it is possible to obtain not only fabrics but also dust proof clothes having electrical conductance throughout the dust proof clothes. Further the sewn portions have been sewn by use of sewing thread containing the conductive fiber, whereby stable electrical conductance can be secured even if puckering occurs after repetition of wearing, washing etc. In other words, in the case where the electrical conductance between the adjacent fabrics in deteriorated due to puckering, the conductive fibers in the fabric and those in the sewing thread are contacted each other, and as a result stable electrical conductance can be secured.
The conductive fibers used in the sewn portions include yarns comprising metal-coated synthetic filaments bicomponent fibers obtained by bicomponent spinning a base polymer as fiber substrate and a conductive polymer having fine particles of a conductive material such as carbon, metal or metal compound dispersed in a matrix polymer. However, fibers covered with a metal or conductive fibers comprising a metal as an conductive component have a problem with durability due to elution or removal of the metal under acidic or alkaline environments, so it is preferable to use the same conductive bicomponent spinned yarn as described above for covering. The latter bicomponent spun fiber using carbon as a conductive material is most preferable.
Insofar as a part of (the conductive polymer containing) the conductive material in the bicomponent fiber is exposed to the surface, the sectional shape are not particularly limited. One example of its sectional shape is shown in FIG. 1.
By way of example, the conductive bicomponent fibers of 1 to 5 denier in finesses as single fiber or of 10 to 200 denier preferably 10 to 100 denier in total fineness is preferably used. The resistance thereof is usually 109 xcexa9/cm or less, particularly 108 xcexa9/cm or less.
As the sewing thread, it is preferable to use that containing 30 to 100% by weight of such conductive bicomponent fibers. If the content of the conductive fibers is 30% by weight or less, it is difficult to obtain a durable electrical conductance stably among sewn portions.
Conductive yarn having such conductive fibers mixed with non-conductive fibers can be used as the sewing thread to attain sewn portions having electrical conductance and being excellent in durability even if puckering occurs in the sewn portions after repetition of wearing, washing etc.
The resistance of such conductive yarn is also preferably 109 xcexa9/cm or less, particularly 108 xcexa9/cm or less. The fineness of the sewing thread is preferably in the range of 180 to 360 denier.
Dust proof clothes produced by sewing the fabrics of the invention with the sewing thread described above, even upon generation of static electricity in any portion of the dust proof clothes, can be easily earthed owing to stable electrical conductance throughout the fabrics and dust proof clothes, and further are excellent in durability and antistatic property.